Exporting the package would be the easiest way I think.
So here is how I got it to work...
blcli_execute BlPackage getDBKeyByGroupAndName "$BLPACKAGE_GROUP" "$BLPACKAGE_NAME"
blcli_execute BlPackage getLocation
I then pass $PKG_PATH/bldeploy.xml to a Java program that parses the xml to get a listing of the file paths. It uses the "<DataFilePath>" for each file to get the filesize of each file. This reads the contents of the bladelogic/NSH/storage/blpackages directory, so it must run on the appserver/fileserver
If anyone is interested in the source listing of the Java app, just email me.
actually - this could run from anywhere that has nsh access to the file server. the location will be a nsh url.